Investigate eslint v9 perf regression

[ssalbdivad]

I recently migrated the repo to v9. All the rules seem to work fine and be responsive in-editor, but the time to run pnpm eslint went from ~8 to ~25 seconds on my machine somehow.

Couldn't immediately figure out what was going on. Generally, linting is only run across the whole repo in CI, so I'm willing to keep up the updated config regardless with the hope there must be some misconfigured setting leading to this.

[ssalbdivad]

Was able to resolve this by reverting from eslint-plugin-import-x to eslint-plugin-import with @eslint/compat.

It was due to un-ts/eslint-plugin-import-x#113

Thanks @JoshuaKGoldberg, @bradzacher for the help diagnosing!